(20 U.S.C. 6301 et. seq.), as amended by this Act, from programs. authorized under the Elementary and Secondary Education Act. of 1965 (20 U.S.C. 6301 et seq.), as in effect on the day before. the date of enactment of this Act.
The efficacy of a vaccine is different from its effectiveness. It is dependent on several factors such as: 1  adherence to vaccine schedules. 2  the disease â some diseases have vaccines against them that perform better than for other diseases. 3  the strain of vaccine â some vaccine strains are more effective than others.
1. How effective is the 2018 flu shot? Early findings from Canada indicate a 17 percent effectiveness against the viral strain, known as H3N2, thatâs been the main culprit of flu in the U.S. this winter. 2. Why are vaccines less protective against some strains of the flu? One reason has to do with the most-common way flu shots are made.